Concentration Averaging and Encapsulation Branch Technical Position, Revision 1

Transcription

1 Concentration Averaging and Encapsulation Branch Technical Position, Revision 1 Volume 1 U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards February 2015

2 Table of Contents 1. INTRODUCTION Purpose of This Guidance Document Document Organization Overview of Concentration Averaging Relationship to Other NRC Guidance SAFETY CULTURE TECHNICAL POSITION Waste Characterization Identifying Waste Streams Identifying Waste Types Physical Characterization Radiological Characterization Blendable Waste Concentration Averaging for a Single Blendable Waste Stream Concentration Averaging for Multiple Blendable Waste Streams Classification of Solidified Waste Discrete Items Concentration Averaging and Classification of Single Discrete Items Concentration Averaging and Classification of Mixtures of Discrete Items Alternative Treatment of Certain Cartridge Filters

3 3.3.4 Encapsulation of Discrete Items Classification of Mixtures of Different Waste Types Determining the Volume or Mass of Waste Quality Assurance Program Alternative Requirements for Waste Classification (10 CFR 61.58) Alternative Approaches for Averaging Site-Specific Intruder Assessments Encapsulation of Discrete Items, Including Sealed Sources Likelihood of Intrusion Large Components Time of Intrusion into Blendable Waste Legacy Wastes Implementation Backfit Considerations REFERENCES APPENDIX A: GLOSSARY APPENDIX B: MAJOR CHANGES FROM 1995 TO 2015 CA BTP APPENDIX C: SAFETY CULTURE STATEMENT OF POLICY Figures Figure 1 CA BTP Guidance Overview Figure 2 Overview of Classification of Mixtures of Discrete Items Figure 3 Classification of Mixtures of Discrete Items Within a Single Waste Type Figure 4 Classification of Sectioned Components Figure 5 Classification of Encapsulated Items

4 Tables Table 1 Thresholds for Demonstrating Adequate Blending Table 2 Recommended Activity Limits of Primary Gamma Emitters Potentially Requiring Piecemeal Consideration in Classification Determinations Table 3 Recommended Activity Limits of Radionuclides other than Primary Gamma Emitters Potentially Requiring Piecemeal Consideration in Classification Determinations Table 4 Volume and Mass for Determination of Concentration

5 1. INTRODUCTION The U.S. Nuclear Regulatory Commission s (NRC s) licensing requirements for land disposal of radioactive waste in Title 10 of the Code of Federal Regulations (10 CFR) Part 61, Licensing Requirements for Land Disposal of Radioactive Waste, include four performance objectives: 10 CFR 61.41, Protection of the general population from releases of radioactivity : 10 CFR 61.42, Protection of individuals from inadvertent intrusion ; 10 CFR 61.43, Protection of individuals during operations ; and 10 CFR 61.44, Stability of the disposal site after closure. A low-level radioactive waste (LLW) disposal facility must be designed, operated, closed, and controlled after closure so that there is reasonable assurance that these performance objectives will be met. This document provides guidance for one aspect related to the 10 CFR performance objective regarding protection of an inadvertent intruder (i.e., the averaging of radionuclide concentrations for determining the classification of the waste). Specifically, this Concentration Averaging (CA) Branch Technical Position (BTP) provides guidance on complying with 10 CFR 61.55(a)(8), Determination of concentrations in wastes, as it applies to the classification of waste for disposal under 10 CFR Part Background In developing the regulations in 10 CFR Part 61, the NRC implemented an approach for managing the risk to an individual who hypothetically could inadvertently intrude on LLW. That approach has a number of different components. Concentration averaging, the subject of this document, is one of those components. First, a 100-year institutional control program is specified in 10 CFR to help ensure that individuals will not intrude into the disposal facility after it is closed. The 100-year period allows for substantial decay of shorter-lived radionuclides so that the remaining hazard is significantly less than when the waste was first disposed. After 100 years, no credit can be taken for the existence of active institutional controls. Next, the NRC postulates that an individual unknowingly intrudes onto the disposal site after the 100-year institutional control period ends and interacts with the waste. To protect this hypothetical 1 individual, the NRC developed a waste classification system in 10 CFR Part 61 that requires segregation of LLW into classes based on radionuclide concentrations, as well as greater control measures for waste with higher radionuclide concentrations. As stated in 10 CFR 61.13, Technical analyses, analyses of the protection of individuals from inadvertent intrusion must include a demonstration that there is reasonable assurance that the waste classification 1 NRC discusses the hypothetical nature of intrusion in the draft Environmental Impact Statement (draft EIS) for 10 CFR Part 61 (NRC, 1981) as well as the final EIS for Part 61 (NRC, 1982). NRC reaffirmed the hypothetical nature of intrusion in the Denial of Petition for Rulemaking Submitted by the New England Coalition on Nuclear Pollution, Docket No. PRM-61-2, March 29, 1994, Agencywide Documents Access and Management System (ADAMS) Accession No. ML

6 requirements will be met. The waste classification requirements are designed to limit the potential radiation exposure to such an intruder to 5 msv/yr (500 mrem/yr). 2 The radiation hazard to an intruder is dependent in part on the particular radionuclides involved and their concentrations. Therefore, 10 CFR Part 61 includes a waste classification system that categorizes waste based on these characteristics of the waste. Three classes (A, B, and C) are defined, and the controls used to manage risk, such as engineered barriers, increase with increasing waste class. Class A waste, the lowest hazard class, has no special provisions for intruder protection, since it contains types and concentrations of radionuclides that typically will decay during the 100-year institutional control period to levels that present an acceptable hazard to an intruder. Class C waste, on the other hand, presents a greater long-term hazard and requires protection for 500 years by an intruder barrier, such as deeper disposal or an engineered structure. The Class A, B, and C waste classes specified in 10 CFR are defined by specific radionuclides and their concentrations. For example, 137 Cs has a Class A limit of Becquerel (Bq) per cubic meter (m 3 ) (1 Curie (Ci) / m 3 ), a Class B limit of Bq/m 3 (44 Ci/m 3 ) and a Class C limit of Bq/m 3 (4600 Ci/m 3 ). The NRC s waste classification system is also generic (i.e., it applies to all LLW disposal sites, regardless of their location in the United States). All generators and waste processors that ship waste to a licensed disposal site must use this system. The 10 CFR waste classification tables do not take into account any site-specific features or considerations, but licensees could perform site-specific or waste-specific intruder analyses in requesting regulatory approval for alternative waste classification provisions (10 CFR 61.58). This CA BTP addresses regulatory considerations for obtaining such approvals (Section 3.7). Like the waste classification system in 10 CFR Part 61, most of the averaging provisions specified in this document are also generic (i.e., they are suitable for use by any licensed disposal facility or generators or processors shipping waste to a licensed disposal facility). This approach might simplify classification for generators, but there might be instances in which generators, processors, or disposal-facility operators (hereafter referred to as licensees ) might decide to apply site-specific averaging approaches. This CA BTP provides examples of site-specific considerations for averaging that might be useful to licensees that propose alternative averaging approaches and to disposal facility regulators that review these proposals. See Section 3.8, Alternative Approaches for Averaging, for additional details. 1.2 Purpose of This Guidance Document The concentration limits for various radionuclides in the 10 CFR Part 61 waste classification system in 10 CFR were developed for average concentrations of wastes. The NRC does not specify in the regulations how radiological hot spots are to be averaged, other than to specify in 10 CFR Part 61.55(a)(8) that averaging of waste 2 This dose limit was used in the draft EIS for 10 CFR Part 61 (NRC, 1981) to develop the waste classification tables in 10 CFR 61.55, Waste classification. 6

7 concentrations is acceptable. 3 The regulations do not define the conditions and constraints 4 on such averaging. This CA BTP is designed to answer questions such as: How much waste above the class limits is permissible in a waste mixture? and How much more concentrated than the limit can a portion of this waste be? and Over what volume are these concentrations to be measured? Because non-radioactive material is also sometimes added to LLW to make it more physically or chemically stable, this CA BTP also answers the question, How much credit can be taken for non-radioactive material that is mixed with LLW? The CA BTP states that extreme measures of adding non-radioactive material, diluting the waste to circumvent stricter disposal requirements, should not be used. All of the constraints on averaging specified in this CA BTP are designed to help ensure that an inadvertent intruder into a disposal site, upon contacting hot spots in waste, will not receive an unsafe exposure to radioactivity. The guidance in this CA BTP may be used to help demonstrate compliance with the following NRC regulations: 10 CFR This provision specifies concentrations of various radionuclides and other instructions for determining the classification of waste. It includes 10 CFR 61.55(a)(8), which states that concentration averaging is permissible in determining waste class. Appendix G, Requirements for Transfers of Low-Level Radioactive Waste Intended for Disposal at Licensed Land Disposal Facilities and Manifests, to 10 CFR Part 20, Standards for Protection Against Radiation, contains several provisions related to the classification of waste. Section C, Disposal Container and Waste Information, item 12, requires that for wastes consigned to a disposal facility, the classification of the waste pursuant to 10 CFR must be documented on the uniform shipping manifest for the waste and each disposal container of waste in the shipment. In addition, Section II, Certification, requires an authorized representative of the waste generator, processor, or collector to certify that the transported materials are properly classified, among other things. This guidance provides acceptable methods that can be used by waste generators, processors, disposal facility operators, Agreement State regulators, and others to perform concentration averaging of specific wastes and mixtures of waste for the purpose of determining their waste class for disposal. Although Agreement States are required to adopt waste classification regulations that are essentially identical to the NRC s in 10 CFR 61.55, 5 they may specify averaging approaches in their disposal facility licenses that differ from those contained in this guidance. 6 Licensees shipping waste for disposal CFR 61.55(a)(8) states that The concentration of a radionuclide may be averaged over the volume of the waste, or weight of the waste if the units are expressed as nanocuries per gram. As used in this document, constraint is used in its normal sense; that is, this guidance recommends limits (or constraints) on how much radionuclide concentrations can be averaged. This guidance is not using the word constraint as it is defined in 10 CFR , Definitions : Constraint (dose constraint) means a value above which specified licensee actions are required. 10 CFR is NRC compatibility Category B. This category is for activities that have direct and significant transboundary implications. In practice, current disposal facility licenses reference the CA BTP in whole or in part. 7

8 may therefore need to consult with disposal facility operators in order to comply with disposal facilities license conditions. Sections represent NRC staff s most recent and best efforts to identify specific concentration averaging methods that will enable licensees to comply with the averaging provision in 10 CFR Part 61.55(a)(8). In Section 3.8, NRC staff gives examples of alternative approaches for averaging, different from those in Sections , that may be also be appropriate, and considerations for licensees and regulators in determining whether such approaches are safe. NRC staff strongly urges licensees to submit proposals for alternative approaches to the regulator for the disposal facility and to have in-depth discussions on the merits of the proposal with the regulator before classifying waste under the alternative provisions. Alternative approaches to averaging are generally complex, often involving selection of intruder scenarios, for example. Detailed discussions between staff of the regulatory agency for the disposal facility and licensee would help to ensure that waste is classified appropriately before shipment to and disposal at a licensed facility. 1.3 Document Organization This CA BTP contains two volumes. Volume 1 is focused on the specific concentration averaging provisions that should be used in classifying waste. Volume 2 contains background information that may be of interest to readers who want to better understand the technical basis for the positions in the first volume. Volume 2 also addresses how issues raised by stakeholders on the 2012 draft of the CA BTP have been addressed by the staff. Volume 1 contains the following sections: Section 1 gives background information, describes the purpose of this CA BTP, describes the organization of the document, provides an overview of concentration averaging, and discusses the relationship between this CA BTP and other NRC guidance. Section 2 describes the NRC s Safety Culture expectations for individuals and organizations performing regulated activities, including the classification of LLW for disposal. Section 3 contains the positions on concentration averaging for a variety of different waste types. It includes the following subsections: o o o Section 3.1 describes considerations for the physical and radiological characterization of waste. Section 3.2 discusses concentration averaging for blendable wastes, which typically do not have significant hot spots that would be a hazard to an inadvertent intruder. Section 3.3 addresses concentration averaging for discrete items of a single waste type. 8

9 o o o o o o o Section 3.4 describes concentration averaging for mixtures of more than one waste type. Section 3.5 identifies the volumes and masses acceptable for using in concentration averaging for various waste streams and types. Section 3.6 describes the quality assurance program that should be used for classifying waste. Section 3.7 discusses the use of 10 CFR 61.58, Alternative requirements for waste classification and characteristics, a regulatory provision which enables licensees to request regulatory approval of waste classification approaches different from those in 10 CFR Section 3.8 discusses potential averaging approaches different from those in the above sections, and considerations for licensees proposals to disposal facility regulators. Section 3.9 describes implementation considerations. Section 3.10 discusses backfit considerations. Section 4 identifies references for Volume 1 of the CA BTP. Volume 1 also contains Appendix A, a glossary; Appendix B, a table which identifies the major changes from the 1995 CA BTP; and Appendix C, the NRC s Safety Culture Policy Statement. Volume 2 of this CA BTP contains the technical basis for the averaging positions in Volume 1, as well as staff responses to public comments on a May 2012 draft of the CA BTP. Staff responses to public comments on previous drafts of the revised CA BTP are available in Appendices C, D, E, and F of the May 2012 draft Overview of Concentration Averaging Concentration averaging is the mathematical averaging of the radionuclide activities in waste over its volume or mass. This CA BTP provides guidance on appropriate volumes and masses to use in calculating average concentrations, as permitted by 61.55(a)(8). Once the average radionuclide concentrations are determined, then the waste classification process described in 10 CFR is used to determine the class of the waste. Figure 1 provides an overview of guidance in this document. This CA BTP addresses two broad categories of waste: blendable waste and discrete items. In general, blendable 7 Available in ADAMS at Accession Number ML

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11 wastes are subject to fewer averaging constraints than discrete items because blendable wastes are generally not expected to have hot spots that could pose a hazard to an inadvertent intruder. 8 In most cases, blendable waste may be averaged over the mass or volume of the waste without any demonstration of adequate blending. In cases in which highly concentrated blendable waste is combined with a blendable waste with much lower radionuclide concentrations, hot spots could be created if the waste is not adequately blended. This CA BTP provides guidance for when waste must be blended and how to demonstrate that waste is adequately blended. The second category is discrete items. The CA BTP recommends constraints for discrete items based on their size and the amount or concentration of radioactivity they contain. The size, amount of radioactivity and concentration help to define the hazard to an inadvertent intruder who might directly handle the discrete item. This CA BTP relies on the following key concepts: Averaging Constraints: Recommended restrictions on averaging radionuclide concentrations as allowed by 10 CFR 61.55(a)(8). Averaging constraints are designed to limit potential hot spots in waste. Different averaging constraints apply to blendable waste and discrete items. Hot Spot: A portion of the overall waste volume whose radionuclide concentrations are above the class limit for the entire container. Because averaging is permitted under the regulations, some exceedance of the limits is permissible for portions of the overall volume of the waste, as long as the average concentration of the container is within the class limit. Classification is based on the average radionuclide concentrations of waste in a container according to 10 CFR 61.55(a)(8), subject to certain constraints on hot spots. Waste Stream: Waste with relatively uniform radiological and physical characteristics. Often, the waste results from a single process. Examples of waste streams are provided in NRC Information Notice (IN) 86-20, Low-Level Radioactive Waste Scaling Factors, 10 CFR Part 61 (ADAMS Accession No. ML ); for example, pressurized-water reactor (PWR) primary and secondary system ion-exchange resins are separate waste streams. Each facility may identify its own waste streams. Waste Type: Wastes with similar physical characteristics but which might have different radiological characteristics. Ion-exchange resins from either the primary or secondary coolant systems in a nuclear power plant are the same waste type. 9 However, ion-exchange resins, soils, and activated metals are different waste types. 8 The BTP guidance for blendable wastes is based on a scenario similar to the post-drilling scenario in National Council on Radiation Protection & Measurements (NCRP) Report Number 152 (NCRP, 2005). The scenario is similar to the agricultural scenarios considered in the Draft Environmental Impact Statement for Part 61 (NRC, 1981) except that less waste is exhumed (see Volume 2, Section 4). 9 As defined in 10 CFR Part 20, and for purposes of this BTP, a waste type is a category of waste within a disposal container having a unique physical description (i.e., a specific waste descriptor code or description; or a waste sorbed on or solidified in a specifically defined media). 11

12 Waste characterization: Waste characterization has many purposes, and in general, it means identifying the physical and radiological properties of LLW. For the purposes of applying the concentration averaging constraints described in this CA BTP, waste characterization includes the identification of the waste stream from which waste is produced (e.g., primary or secondary resins in a nuclear power plant), the waste type (i.e., wastes with similar physical characteristics), physical characterization (e.g., whether waste is discrete or blendable, and radiological characterization (i.e., the determination of the presence and concentrations and amounts of radionuclides relevant to waste classification. Waste classification: the process of categorizing waste based on the concentration of certain key radionuclides important to protection of an inadvertent intruder into a LLW disposal facility. 10 CFR Part 61 defines three classes (A, B, and C). The controls used to manage risk to an inadvertent intruder, such as engineered barriers, increase with increasing waste class. Discrete Items: For the purposes of this CA BTP, discrete items are items belonging to one of the following waste types: activated metals, sealed sources, cartridge filters 10, contaminated materials, and components incorporating radioactivity into their design. Items belonging to these waste types are designated as discrete items in this guidance because (1) they are expected to be durable (i.e., remain intact at the time of intrusion) and (2) items belonging to these waste types often have relatively high amounts or concentrations of radioactivity. Blending: Blending is physically mixing two or more blendable waste streams to create a product with relatively uniform radionuclide concentrations. For the purposes of this CA BTP, a waste stream is considered to have the properties needed for blending (i.e., a waste stream is blendable ) if: (1) the waste can be physically mixed to create relatively uniform 11 radionuclide concentrations or (2) the waste is not expected to contain durable items with significant activity. 12 This CA BTP makes a distinction between waste that is blendable, indicating that it has the properties needed for blending, and waste that is blended, indicating two or more blendable waste streams have been physically mixed together. Encapsulation: The process of surrounding a radioactive sealed source, a collection of such sources, or other materials in a binding matrix within a container, where the activity remains within the dimensions of the original source(s) or other materials. This CA BTP provides guidance on the amount of encapsulating material can be included in concentration averaging As described in Section 3.3.3, cartridge filters may be treated as blendable waste in some cases. Radionuclide concentrations are relatively uniform if an intruder who encounters the waste is unlikely to encounter waste more concentrated than the class limit by a factor of 10. Durable items with significant activity are defined as discrete items. Although contaminated trash may contain durable items, any durable items in trash are not expected to contain significant activity. Durable items with significant contamination are considered to be contaminated materials instead of trash. 12

13 Alternative Approaches: The averaging constraints specified in this CA BTP are generic, like the 10 CFR Part 61 waste classification system, and are suitable for use at any disposal facility. This CA BTP also provides guidance for alternative approaches to concentration averaging based on site- or waste-specific considerations that licensees may propose to the disposal facility regulator. These terms and others important to this CA BTP are listed in the glossary in Appendix A. 1.5 Relationship to Other NRC Guidance This CA BTP has evolved from a section in a guidance document published shortly after 10 CFR Part 61 was promulgated. The NRC s Final Waste Classification and Waste Form Technical Position Papers (NRC, 1983) described overall procedures acceptable to the NRC staff that could be used to determine the presence and concentrations of the radionuclides listed in 10 CFR That information was also used by licensees to classify waste for near-surface disposal. The 1983 Technical Position on Waste Classification included Section C.3, Concentration Volumes and Masses, which provided guidance to waste generators on the interpretation of 10 CFR 61.55(a)(8), Determination of concentrations in wastes. This provision allows averaging of waste concentrations for determining the classification of the waste as Class A, B, or C. On January 17, 1995, the NRC replaced Section C.3 of the 1983 Technical Position on Waste Classification with the Branch Technical Position on Concentration Averaging and Encapsulation (NRC, 1995a). A major purpose of the 1995 CA BTP was to provide guidance for the disposal of discrete, durable, gamma-emitting items or mixtures of such items. The 1995 guidance was designed to ensure that potential exposures from exhuming discrete items would be within the envelope of safety considered for inadvertent intrusion in the environmental impact statement (EIS) for Part 61. The EIS for Part 61 did not explicitly consider potential intruder exposures from discrete items. Instead, it considered the potential exposure of an inadvertent intruder who lives and grows food on a site where waste has inadvertently been exhumed and mixed with soil. This document updates the 1995 CA BTP in its entirety. 13 However, some of the remaining guidance in the 1983 Technical Position on Waste Classification remains in effect. Specifically, Section C, Regulatory Position (including Sections C.1, General Criteria; and C.2, Determination and Verification of Radionuclide Concentrations and Correlations ), and Appendix A, General Program for Classifying Wastes at Nuclear Power Plants, may continue to be used. As noted above, this 2015 document replaces Section C.3 addressing concentration averaging. 14 In addition, Section C.4, Reporting on Manifests has been superseded by a waste manifesting rule promulgated on March 28, 1995, Low-Level Waste Shipment Manifest Information and Reporting, (NRC 1995b). Guidance for implementing that rule is contained in NUREG/BR-0204, Instructions for Completing NRC s Uniform Low-Level Radioactive Waste Manifest (NRC, 1998b) As discussed in Section 3.10, use of this revised guidance is voluntary. Licensees and applicants may choose another method of demonstrating compliance with 10 CFR 61.55(a)(8). In particular, current licensees may continue to use the 1995 CA BTP. Corrections to the 1983 guidance identified in the 1995 BTP remain in effect, however. Specifically, in p. 6, fourth line, and p. 12, second paragraph, fifth line, replace biannual with biennial. 13

14 The scope of this revised CA BTP is limited to the averaging of concentrations of radionuclides for the purpose of determining the classification of waste being shipped for disposal, as provided for by 10 CFR 61.55(a)(8). Licensees shipping waste for disposal must meet other requirements, including the disposal facility license conditions, and should follow other applicable NRC guidance documents that cover other aspects of LLW transportation and disposal (e.g., hydrogen generation 15 and waste form stability 16 ). 2. SAFETY CULTURE It is the NRC s expectation that individuals and organizations performing regulated activities, such as characterizing and classifying LLW for disposal, establish and maintain a positive safety culture commensurate with the safety and security significance of their activities and the nature and complexity of their organizations and functions. This applies to all licensees, certificate holders, permit holders, authorization holders, holders of quality assurance program approvals, vendors and suppliers of safety-related components, and applicants for a license, certificate, permit, authorization, or quality assurance program approval, subject to NRC authority. Nuclear safety culture is defined as the core values and behaviors resulting from a collective commitment by leaders and individuals to emphasize safety over competing goals to ensure protection of people and the environment. Individuals and organizations performing regulated activities bear primary responsibility for safely handling and securing these materials. Experience has shown that a positive safety culture exhibits certain personal and organizational traits. A trait, in this case, is a pattern of thinking, feeling, and behaving that emphasizes safety, particularly in goal conflict situations (e.g., production versus safety, schedule versus safety, and cost of the effort versus safety). The NRC, as the regulatory agency with an independent oversight role, reviews the performance of individuals and organizations to determine compliance with requirements and commitments through its existing inspection and assessment processes. Licensees are not required by the regulations to incorporate the NRC s safety culture policy statement into their activities. However, many of the safety culture traits may be inherent to an organization s existing radiation safety practices and programs. Refer to Appendix C for the NRC s Safety Culture Policy Statement. More information on NRC activities related to safety culture can be found at: 3. TECHNICAL POSITION This section provides guidance on acceptable methods of concentration averaging for classification of low-level radioactive waste in accordance with 10 CFR 61.55(a)(8). It also provides guidance on characterization and classification of waste for waste manifests contained in Appendix G to 10 CFR Part See Information Notice 84-72, Clarification of Conditions for Waste Shipments Subject to Hydrogen Gas Generation, (NRC, 1984). See Revision 1 of the Waste Form Technical Position (NRC, 1991). 14

15 3.1 Waste Characterization Waste must be characterized to determine which averaging constraints apply for waste classification. In addition, LLW generators shipping waste for disposal, either directly or through a waste processor or collector, are required to characterize waste on the uniform shipping manifests prescribed in Appendix G to 10 CFR Part For the purposes of this CA BTP, waste is divided into one of two categories, blendable waste or discrete items. Different averaging constraints apply to each category. Discrete items are generally individually characterized, and therefore more characterization is required for discrete items than for blendable wastes Identifying Waste Streams Waste is considered to be from a single waste stream if it has relatively uniform radiological and physical characteristics. Often, a waste stream results from a single process. Waste streams are considered distinct (i.e., different from one another) if the concentrations of radionuclides of concern (see the Glossary) typically differ by more than a factor of 10 (e.g., primary and secondary resins from nuclear power plants are distinct waste streams). NRC IN 86-20, Low Level Radioactive Waste Scaling Factors, 10 CFR Part 61 (NRC, 1986a), provides a list of typical waste streams at nuclear power plants. For example, for pressurized-water reactors (PWRs), IN identifies these separate waste streams: primary purification filters, primary purification resins, chemical and volume control system evaporator bottoms, radwaste polishing resins, secondary system wastes (filters and resins), and contaminated trash. For Boiling Water Reactors (BWRs), IN identifies these separate waste streams: cleanup filters and resins, condensate-polishing resins, evaporator bottoms, radwaste ion-exchange resins, and contaminated trash. These lists are provided only as examples and licensees may identify waste streams differently Identifying Waste Types Waste is considered to be a single waste type if the waste has relatively uniform physical characteristics. For example, primary resin and secondary resin are the same waste type but resin and soil are different waste types Physical Characterization Most LLW shipped for disposal is in a solid waste form and is subject to concentration-averaging constraints based on whether it is blendable waste or discrete items. Small amounts of gaseous waste may also be disposed of but are not subject to concentration-averaging constraints because the radiological concentrations in gases are expected to be uniform. Liquid waste, other than small amounts of free liquid in 17 A waste shipping manifest is not required from the generator when the radioactively contaminated material sent by a licensee becomes the waste processor s residual waste. Residual waste is defined in Appendix G, 10 CFR Part 20, to mean low-level radioactive waste resulting from processing or decontamination activities that cannot be easily separated into distinct batches attributable to specific waste generators. This waste is attributable to the processor or decontamination facility, as applicable. 15

16 containers, is not authorized for disposal in a licensed disposal facility. However, liquid waste may be solidified or absorbed onto solid media in preparation for disposal. 18 Blendable waste (see Section 3.2) includes waste types such as soils, resins, filter media, compactible trash, non-compactible trash, and ash. Blendable waste is not expected to contain discrete durable items that would be a hazard to an inadvertent intruder. For the purposes of this CA BTP, discrete items (see Section 3.3) are items belonging to one of the following waste types: activated metals, sealed sources, cartridge filters, 19 contaminated materials, and components incorporating radioactivity into their design. Items belonging to these waste types are designated as discrete items in this guidance because (1) they are expected to be durable (i.e., remain intact at the time of intrusion) and (2) items belonging to these waste types often have relatively high amounts or concentrations of radioactivity. Process knowledge may be used to determine whether items are expected to have high amounts or concentrations of radioactivity. Another physical characteristic important for waste classification is the volume to be used for the purposes of concentration averaging. Table 4 in Section 3.5 identifies constraints for the volume or mass that should be used in classifying waste. Most concentrations of radionuclides in the 10 CFR waste classification tables are based on radioactivity per unit volume. 20 Weight may also be used and converted to equivalent volume for averaging purposes provided that a representative density is used, based on a representative distribution of materials Radiological Characterization Sections C.1, General Criteria, and C.2, Determination and Verification of Radionuclide Concentrations and Correlations, of the 1983 Technical Position on Waste Classification describe acceptable procedures to determine the presence and concentrations of the radionuclides listed in 10 CFR As noted earlier, the concentration averaging guidance in Section C.3 of that 1983 document was replaced by the 1995 CA BTP, which has been updated in its entirety by this revised CA BTP. 22 However, Sections C.1 and C.2 of the 1983 guidance are still in effect. Section C.2 of the 1983 Technical Position on Waste Classification identifies four different methods for radiological characterization of waste: (1) compliance through materials compatibility, (2) classification by source, Liquid waste may also be disposed of as a liquid effluent in accordance with the provisions of 10 CFR Part 20. This BTP only covers solid waste shipped for disposal at a licensed facility. As described in Section 3.3.3, cartridge filters may be treated as blendable waste in some cases. Transuranic radionuclide concentration limits are specified as radioactivity per unit of weight. Other NRC guidance on radionuclide characterization may be used as well (see, for example, Information Notice 86-20, Low-Level Radioactive Waste Scaling Factors, 10 CFR Part 61 (NRC, 1986a)). The 1983 Technical Position on Waste Classification is NRC s principal guidance on radionuclide characterization for the purposes of waste classification, however. As discussed in Section 3.10, use of this guidance is voluntary. Licensees and applicants may choose another method of demonstrating compliance with 10 CFR 61.55(a)(8). In particular, current licensees may continue to use the 1995 CA BTP. 16

17 (3) gross radioactivity measurements, and (4) measurement of specific radionuclides. The extent of radiological characterization required depends on whether the wastes are blendable wastes or discrete items. Discrete items should generally be individually characterized because they are subject to averaging constraints in this CA BTP. Blendable waste generally requires less characterization than discrete items. In some cases, blendable wastes (e.g., contaminated trash) may include durable items that have low activity of gamma-emitting radionuclides. These items do not need to be individually characterized, as explained in Section 3.2. In a few cases, mixtures of distinct blendable waste streams should be shown to be adequately blended, as discussed in Section For radiological characterization of contaminated materials (i.e., components or metals on which radioactivity resides near the surface in a fixed or removable condition), the staff provides the following guidance. For individual items, classification may be determined by representative swipes or radiation survey measurements from which the total activity of radionuclides may be estimated through the use of scaling factors. In these cases, the volume or weight of the contaminated material should be the total mass or displaced volume of the item (i.e., major void volumes subtracted from envelope volume). For mixtures of these contaminated items, the total activity of contained radionuclides may also be determined by representative 23 swipes or radiation survey measurements of the container s contents. The volume or mass of the mixture should be the total mass or displaced volume of all the material contributing to the mixture. It is also permissible under the constraints for discrete items in Section 3.3 to average concentrations of the radionuclides listed in Tables 1 and 2 of 10 CFR over the contents of the disposal container. If generators are shipping to a waste processor or collector, they do not need to classify the waste, because classification is only required for the final waste form presented for disposal. However, waste processors or collectors might need to rely on the physical and radiological characterization provided by generators for classifying the waste for disposal. 3.2 Blendable Waste For the purposes of this guidance, a waste type is considered to have the properties needed for blending (i.e., a waste type is blendable ) if: the waste can be physically mixed to create relatively uniform 24 radionuclide concentrations or the waste is not expected to contain durable items with significant activity For swipes or radiation survey measurements to be representative of the mixture, discrete items in the mixture should meet the Factors of 2 and 10 described in Section 3.3, as appropriate for the mixture. Radionuclide concentrations are relatively uniform if an intruder who encounters the waste is unlikely to encounter waste more concentrated than the class limit by a factor of 10 or more. 17

18 This CA BTP makes a distinction between waste that is blendable, indicating it has the properties needed for blending, and waste that is blended, indicating two or more blendable waste streams have been physically mixed together. Different waste types (e.g., resins and soils) can be blended if the licensee documents the physical and chemical compatibility of the waste types being combined (see Section 3.2.2). A waste type can be considered blendable if it meets either of the criteria listed in the previous paragraph. Ion-exchange resins, filter media, evaporator bottom concentrates, soil, and ash are each an example of a blendable waste type for the purposes of concentration averaging because each of these waste types, individually, can be physically mixed to create relatively uniform radionuclide concentrations. Contaminated trash is considered to be blendable because it is not expected to contain durable items with significant activity. 25 Process knowledge may be used to determine whether items are expected to have radioactivity in high amounts or concentrations. Similarly, those cartridge filters that can be demonstrated (e.g., through process knowledge) not to contain primary gamma emitters in excess of the values in Table 2 may be treated as blendable waste for the purposes of concentration averaging 26 (see Section 3.3.3). As used in this CA BTP, the primary gamma-emitting nuclides are cobalt-60 ( 60 Co), niobium-94 ( 94 Nb), and cesium-137 ( 137 Cs) Concentration Averaging for a Single Blendable Waste Stream If a waste package contains a single blendable waste stream, radionuclide concentrations for waste classification may be averaged over the waste in the package. That is, an average radionuclide concentration may be based on its total activity in the package divided by the volume 28 or mass of the waste in the package. However, if waste fills 90 percent or more of a package, average radionuclide concentrations can be based on the entire interior volume of the container. Void spaces do not normally need to be accounted for in blendable waste 29. Absorbed liquid (i.e., liquid radioactive waste that is absorbed onto an absorbent medium) may not be retained on the absorbent medium. Therefore, radionuclide concentrations should not be based on the volume or mass of the absorbent medium, but should be based on the original volume or mass of the liquid waste before absorption. The activity of small concentrated sources or gauges (less than 3.7 MBq) (100 µci) that may be mixed with contaminated trash may be averaged over the trash volume The definition of discrete items in this CA BTP (i.e., activated metals, sealed sources, cartridge filters, contaminated materials, and components incorporating radioactivity into their design) is expected to cover all durable items with significant activity. Note that the requirements in Section I.C.10 of Appendix G to 10 CFR Part 20 related to cartridge filters and contaminated equipment continue to apply even though these items may be treated as blendable waste for the purposes of concentration averaging. Most 137 Cs decays to a metastable nuclear isomer, 137m Ba. 137 Cs is not a gamma emitter, but 137m Ba is. When this BTP refers to 137 Cs, it includes the 137m Ba that is in equilibrium with it. The volume of the waste can be calculated from the weight of the waste divided by its density. Licensees may use a representative density based on a representative distribution of materials as they occur in waste. The staff expects that in most cases it would not be consistent with as low as is reasonably achievable (ALARA) principles to determine the internal void spaces in contaminated trash. 18

19 3.2.2 Concentration Averaging for Multiple Blendable Waste Streams In some cases, blendable waste streams of the same waste type (e.g., primary and secondary resins) may be combined in the same container without blending. If the CA BTP Table 1 thresholds are not exceeded, the waste does not need to be blended and the radionuclide concentrations can be averaged over the volume of the waste or container as a single waste stream (i.e., as in Section 3.2.1). If the thresholds in CA BTP Table 1 are exceeded, the waste must be blended and a demonstration of adequate blending is needed. These thresholds are based on the sum of fractions of the most concentrated influent waste stream, the volume of the mixture, and the classification of the final mixture. Waste is adequately blended if there is reasonable assurance that there are no hot spots of waste 0.2 m 3 (7 cubic feet (ft 3 )) or larger in size that have a sum of fractions greater than 10 relative to the blended product. Alternative approaches for demonstrating blending is adequate may be justified based on site-specific conditions (see Section 3.8). Radionuclide concentrations should not be averaged over more than one container. An explanation and example of determining the sum of fractions is provided in 10 CFR 61.55(a)(7). In summary, the first step in determining Sum of Fractions of the Most Concentrated Influent Waste Stream listed in this revised CA BTP Table 1 is to determine the intended waste class of the blended product. Then the licensee should take the concentration of each nuclide in the most concentrated influent waste stream and divide it by the 10 CFR Part 61 concentration limit for that radionuclide, based on the waste class of the final blended product. The licensee should then sum the fractions over all the radionuclides in the influent waste stream. For example, if a licensee is blending waste to produce Class A waste, and the most concentrated influent waste stream has a 60 Co concentration of 20,000 Ci/m 3, the licensee would divide 20,000 Ci/m 3 by the 10 CFR Table 2 Column 1 (Class A) limit for 60 Co of 700 Ci/m 3. If 60 Co were the only radionuclide in the most concentrated influent waste stream, then the Sum of Fractions of the Most Concentrated Influent Waste Stream would be 20,000 Ci/m 3 divided by 700 Ci/m 3, which is 28. In this case, based on the CA BTP Table 1, the licensee would either need to limit the volume the waste is averaged over to less than 60 m 3 (2,100 ft 3 ) or provide a demonstration of adequate blending. A demonstration that waste is adequately blended can be based on process knowledge, reasoned conclusions, calculations, or direct measurements. For example, a licensee can show that a particular process blends waste adequately by testing the process with physically similar 30 but nonradioactive materials (e.g., resins colored with dye tracers). Direct measurements are not necessarily preferable to indirect methods because direct measurements are likely to require 30 In this context, physically similar refers to characteristics that could affect physical mixing (e.g., particle size or liquid content). 19

20 Table 1. Thresholds for Demonstrating Adequate Blending Characteristics of Most Concentrated Influent Waste Stream Class A Mixture Volume of Mixture in m 3 (ft 3 ) Class B Mixture Class C Mixture Sum of fractions less than 10 Sum of fractions between 10 and 20 Sum of fractions between 20 and 30 Sum of fractions between 30 and 50 Sum of fractions between 50 and 100 No limit No limit No limit No limit No limit 50 (1800) 60 (2100) No limit* 20 (700) 20 (700) No limit* 6 (210) 6 (210) 40 (1400)* 2 (70) Licensees using larger averaging volumes or more concentrated influent waste streams should demonstrate the waste has been adequately blended (see Section 3.2.3). Sum of fractions is based on the class of the blended product. * In the draft EIS for Part 61, class limits were derived based on a dose calculation. In the final EIS for Part 61, adjustments were made differently to the Class A, B, and C limits (see Volume 2, Section 4.6). closer proximity to the waste than indirect methods. Therefore, making direct measurements may not be consistent with as low as is reasonably achievable (ALARA) principles if indirect methods are available that can quantify relevant radionuclide concentrations adequately. If multiple waste streams of a single waste type generated 31 at a licensee s facility are aggregated for the purposes of operational efficiency, occupational safety, or occupational dose reduction, the aggregated waste can be treated as a single waste stream for the purposes of this CA BTP (see Section 3.2.2). Table 1 of the CA BTP does not apply to this aggregated waste and no demonstration of adequate blending is needed. This reasoning does not apply to wastes that are blended after they have already been packaged separately for shipping (e.g., from a generator to a processor) a demonstration of adequate blending may be necessary for such wastes. Licensees combining one or more blendable waste types with each other or with discrete waste types (e.g., combining ion-exchange resins with soils, or ion-exchange resins with cartridge filters) should document the physical and chemical compatibility of the waste types and make the documentation available for inspection. Wastes that could interact to cause undesirable chemical reactions (e.g., unacceptable amounts of hydrogen 31 This provision is not intended to apply to waste processors. 20

21 generation) should not be combined. 32 Additional constraints may be necessary to meet the Waste Acceptance Criteria of a specific disposal facility. The 1983 Technical Position on Waste Classification indicates that more sophisticated waste classification analyses should be used for waste for which minor process variations may cause a change in waste classification. For example, if one or more influent waste streams in a blending process are much more concentrated than the waste class of the blended product, there is an increased chance of misclassifying waste because of radiological hot spots. If no practical means exist of demonstrating that waste streams are adequately blended, licensees should not exceed the threshold volumes in Table Classification of Solidified Waste Solidification is the process of incorporating radioactive waste into a binding matrix to create a solid, physically and radiologically uniform waste form. 33 Examples of solidified waste include solidified liquids, solidified ion-exchange resins, and solidified shredded cartridge filters. Both NRC guidance (NRC, 1991) and industry standards (American National Standards Institute (ANSI)/American Nuclear Society (ANS)-55.1) state that solidified waste should be adequately mixed to produce a physically uniform product. The NRC staff expects that the degree of mixing required to create a physically uniform product will also eliminate radiological hot spots. Therefore, if solidification is performed to create a physically uniform waste form in accordance with NRC guidance for solidification and industry standards, the average radionuclide concentrations in solidified waste may be based on the total volume or mass of the solidified waste form. As discussed in Section 3.5, nonradioactive materials used in solidification should have a purpose (e.g., stabilization of waste), other than lowering the waste class. 3.3 Discrete Items This section provides guidance on the classification of discrete items. For the purposes of this CA BTP, discrete items are items belonging to one of the following waste types: activated metals, sealed sources, cartridge filters, contaminated materials, and components incorporating radioactivity into their design. Items belonging to these waste types are designated as discrete items in this guidance because (1) they are expected to be durable (i.e., remain intact at the time of intrusion) and (2) items belonging to these waste types often have relatively high amounts or concentrations of radioactivity. This position applies to classifying a container of items of a single waste type and includes a number of criteria to ensure that individual items are unlikely to compromise the safety of an inadvertent intruder Concentration Averaging and Classification of Single Discrete Items Individual discrete items may be classified based on the activity of their 10 CFR radionuclides divided by the volume or weight of the item, as applicable. If an individual item is encapsulated, the concentration may be averaged over the volume or weight of the See, e.g., Information Notice 84-72, Clarification of Conditions for Waste Shipments Subject to Hydrogen Gas Generation. (NRC, 1984). Encapsulation is different from solidification in that a discrete item is placed in a non-radioactive matrix without creating a uniform concentration of radioactivity. 21